Recent developments in the design and processing of gamma-based titanium aluminide alloys

Intermetallic titanium aluminides exhibit attractive thermophysical properties which give them the potential for extensive use as lightweight structural components. Demands for higher strength coupled with good oxidation resistance have initiated significant efforts in the design and processing of these alloys. Novel design concepts are based on alloys with the general composition (in at. %) Ti-45Al-(5-10)Nb, which were subjected to solid solution and precipitation hardening. Optimised compositions have been identified that are capable of carrying stresses in excess of 700 MPa at service temperatures of 700 degreesC and exhibit superior creep properties Thus, wrought alloys of this type can be an attractive alternative to the nickel base superalloys in certain ranges of stress and temperature. The future and promise of these of the new TiAl alloys lies in innovative processing methods designed to achieve better performance. These concerns are addressed in the present paper through global commentary on the physical metallurgy and processing, using the results generated primarily at our laboratory.